Abstract: ZL is a C++-compatible language in which high-level constructs, such as classes, are defined using macros over a C-like core language. This approach makes many parts of the language easily customizable. For example, since the class construct can be defined using macros, a programmer can have complete control over the memory layout of objects. Using this capability, a programmer can mitigate certain problems in software evolution such as fragile ABIs (Application Binary Interfaces) due to software changes and incompatible ABIs due to compiler changes. In this paper, we outline the problem of fragile and incompatible ABIs and show how ZL can be used to solve them.